Body fluids and the stains they leave at crime scenes Serology Body fluids and the stains they leave at crime scenes 2009©Forensic Science Today

Common Types of Serology Commonly found rape cases are: Blood Hair Sperm 2009©Forensic Science Today

History of Blood Typing 1901- Karl Landsteiner, recognized differences in human blood Received Nobel Prize in 1929 Critical in blood transfusions A-B-O classification system Rh factor in blood was demonstrated in 1937 More than 100 different blood factors are known today. 2009©Forensic Science Today

2009©Forensic Science Today True or False No two individuals, except for identical twins, could be expected to have the same combination of blood factors. 2009©Forensic Science Today

2009©Forensic Science Today Prior to 1990, A-B-O system provided the best means for forensic scientists to link blood to an individual. What changed in 1990? 2009©Forensic Science Today

2009©Forensic Science Today Components of Blood Cellular-Solid materials suspended in plasma that makes up 45% of “blood” Red Blood Cells (RBC)-erythrocytes White Blood Cells (WBC)-leukocytes Platelets Plasma – 55%- fluid portion of unclotted blood-mostly water Antibodies Enzymes Proteins Serum= liquid that separates from the blood when a clot is formed 2009©Forensic Science Today

Blood Stains on Victim’s Jeans Sections removed & initialed for testing 2009©Forensic Science Today

Forensic Characterization of Bloodstains Is it blood? From what species did it originate? If the blood is of human origin, how closely can it be associated to a particular individual? 2009©Forensic Science Today

Species Identification Prior to 1990, double immuno-diffusion plate was used for species identification of blood stains. Today scientists simply test using DNA techniques 2009©Forensic Science Today

Techniques to Visualize Kastle-Meyer – uses H2O2 + phenolphthalein to produce a bright pink color in the detection of peroxidase activity in blood Leucomalachite green. Leucomalacite green is dropped on the suspect stain. A positive blood result will immediately turn the swab greenish-blue. 2009©Forensic Science Today

2009©Forensic Science Today More Visualization Tetramethylbenzidine- test by placing drops on a suspect stain. A positive reaction is indicated by an intense blue color.   Luminol- Luminol is also a field test that you may have seen on one of the forensic investigation television shows. It involves spraying the chemical onto the suspected bloodstain and viewing it in total darkness. If blood is present, it will begin to luminesce (glow a whitish-blue) within 5 seconds. 2009©Forensic Science Today

2009©Forensic Science Today Luminol Test Extremely Sensitive- capable of detecting bloodstains diluted up to 300,000 times Large areas are sprayed and viewed in darkened areas for emission of light Does not interfere with subsequent DNA testing http://www.flickr.com/photos/jackofspades/4376209354/ Figure 12-5 p. 337 Saferstein Criminalistics, 2004 2009©Forensic Science Today

A Bloody Knife from a Homicide Scene. Here a forensic serologist will sample areas she believes may contain blood and test them for the presence of blood using the Kastle-meyer, or other visualization techniques. If the results of the test are positive the stain will be collected with a swab and placed in storage (refrigerated at -80F) for DNA testing. 2009©Forensic Science Today

From what species did it originate? Preciptin Test >Very sensitive >Requires only a small sample >Even dried bloodstains from 10-15 years ago can be tested. >Positive test results even in diluted samples Gel diffusion See pp. 338-339 Saferstein, Criminalistics, 2004. 2009©Forensic Science Today

Applications of Genotyping Blood Factors No direct relevance to Criminal Investigations Paternity Testing Blood type may clear a suspect Example: Child is type AB Mother is type AB Suspected Father is type O Draw the Punnett Square. 2009©Forensic Science Today

2009©Forensic Science Today Rape Statistics http://www.rainn.org/statistics 2009©Forensic Science Today

Forensic Characterization of Semen Locate the stain and screen for semen with the acid phosphatase color test Acid phosphatase is an enzyme present in high concentrations in semen Suspect stain is transferred to filter paper; reagent is added. If semen is present, sample will fluoresce under UV light within 30 seconds. http://www.houstonpi.com/sementrace/videos.html 2009©Forensic Science Today

Microscopic Examination Semen can be identified by the presence of spermatazoa @ 400x magnification 2009©Forensic Science Today

Challenges for the Microscopist Sample collection: Sperm bind tightly to cloth materials, are extremely brittle when dry, and disintegrate if the stain is washed or rubbed against another object Oligospermia – abnormally low sperm count (prefix Oligo means “just a few or scant” Aspermia- absence of sperm or sterility (partly due to growing popularity of vasectomies) 2009©Forensic Science Today

p30 or Prostate Specific Antigen Protein discovered in 1970’s Unique to seminal plasma See Criminalistics pp. 351 & 352 Figure 12-6 and Figure 12-17 for PSA testing by precipitation and electrophoresis If semen is present, DNA testing is used to link seminal material to an individual. More later. . . . 2009©Forensic Science Today

Collection of Rape Evidence Forceful physical contact between victim and assailant may result in the transfer of hair, fibers, blood, and semen (Locard’s Exchange Principle) Carefully package all outer garments and undergarments separately in PAPER bags. Victim should stand on paper while undressing so that any loose fibers can be collected for analysis. Collect bedding, if appropriate 2009©Forensic Science Today

Collection of Rape Evidence Disposable latex gloves are essential for handling evidence! DNA may be transferred through perspiration. Investigators must avoid direct personal contact with evidence. 2009©Forensic Science Today

Victim needs a medical exam ASAP! Evidence collection kit includes Pubic combings & standard/reference samples External genital skin areas Vaginal swabs & smear Cervix swabs Rectal swabs & smear Oral swabs & smear Head hairs Blood sample Fingernail scrapings All clothing Urine specimen (for drug testing e.g. Rohypnol, GHB) Swab of any area that may have assailant’s saliva for DNA testing See Saferstein, Criminalistics, 2004, p. 353 2009©Forensic Science Today

Evidence from Suspect, if apprehended All clothing Pubic Hair combings Pulled head and pubic hair standard/reference samples Penile swab taken within 24 hours after assault Blood sample or buccal swab for DNA testing 2009©Forensic Science Today

2009©Forensic Science Today DNA Testing Extremely sensitive- characterization possible with only 1 billionth of a gram of sample 2009©Forensic Science Today

2009©Forensic Science Today Timing Sperm can survive up to 4-6 hours in the vaginal cavity of a living female. Time of sexual attack may be determined. Nonmotile sperm may be found up to 3 days after intercourse. Acid phosphatase can be detected in the vaginal cavity for up to 48 hours after intercourse. p30 can be detected for 24 hours. 2009©Forensic Science Today

2009©Forensic Science Today